Previous HGNC Symbols for ABCB4 Gene

Previous GeneCards Identifiers for ABCB4 Gene

Summaries for ABCB4 Gene

Entrez Gene Summary for ABCB4 Gene

The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MDR/TAP subfamily. Members of the MDR/TAP subfamily are involved in multidrug resistance as well as antigen presentation. This gene encodes a full transporter and member of the p-glycoprotein family of membrane proteins with phosphatidylcholine as its substrate. The function of this protein has not yet been determined; however, it may involve transport of phospholipids from liver hepatocytes into bile. Alternative splicing of this gene results in several products of undetermined function. [provided by RefSeq, Jul 2008]

UniProtKB/Swiss-Prot for ABCB4 Gene

Energy-dependent phospholipid efflux translocator that acts as a positive regulator of biliary lipid secretion. Functions as a floppase that translocates specifically phosphatidylcholine (PC) from the inner to the outer leaflet of the canalicular membrane bilayer into the canaliculi of hepatocytes. Translocation of PC makes the biliary phospholipids available for extraction into the canaliculi lumen by bile salt mixed micelles and therefore protects the biliary tree from the detergent activity of bile salts (PubMed:7957936, PubMed:8898203, PubMed:9366571, PubMed:17523162, PubMed:23468132, PubMed:24806754, PubMed:24723470, PubMed:24594635, PubMed:21820390). Plays a role in the recruitment of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM) molecules to nonraft membranes and to fu rther enrichment of SM and cholesterol in raft membranes in hepatocytes (PubMed:23468132). Required for proper phospholipid bile formation (By similarity). Indirectly involved in cholesterol efflux activity from hepatocytes into the canalicular lumen in the presence of bile salts in an ATP-dependent manner (PubMed:24045840). Promotes biliary phospholipid secretion as canaliculi-containing vesicles from the canalicular plasma membrane (PubMed:9366571, PubMed:28012258). In cooperation with ATP8B1, functions to protect hepatocytes from the deleterious detergent activity of bile salts (PubMed:21820390). Does not confer multidrug resistance (By similarity).

Alternative splice isoforms for ABCB4 Gene

neXtProt entry for ABCB4 Gene

Protein Expression for ABCB4 Gene

Post-translational modifications for ABCB4 Gene

Phosphorylated (PubMed:24723470). Phosphorylation on Thr-34 is required for PC efflux activity. Phosphorylation occurs on serine and threonine residues in a protein kinase A- or C-dependent manner (PubMed:24723470). May be phosphorylated on Thr-44 and Ser-49 (PubMed:24723470).

Function for ABCB4 Gene

Products:

Molecular function for ABCB4 Gene

UniProtKB/Swiss-Prot Function:

Energy-dependent phospholipid efflux translocator that acts as a positive regulator of biliary lipid secretion. Functions as a floppase that translocates specifically phosphatidylcholine (PC) from the inner to the outer leaflet of the canalicular membrane bilayer into the canaliculi of hepatocytes. Translocation of PC makes the biliary phospholipids available for extraction into the canaliculi lumen by bile salt mixed micelles and therefore protects the biliary tree from the detergent activity of bile salts (PubMed:7957936, PubMed:8898203, PubMed:9366571, PubMed:17523162, PubMed:23468132, PubMed:24806754, PubMed:24723470, PubMed:24594635, PubMed:21820390). Plays a role in the recruitment of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM) molecules to nonraft membranes and to fu rther enrichment of SM and cholesterol in raft membranes in hepatocytes (PubMed:23468132). Required for proper phospholipid bile formation (By similarity). Indirectly involved in cholesterol efflux activity from hepatocytes into the canalicular lumen in the presence of bile salts in an ATP-dependent manner (PubMed:24045840). Promotes biliary phospholipid secretion as canaliculi-containing vesicles from the canalicular plasma membrane (PubMed:9366571, PubMed:28012258). In cooperation with ATP8B1, functions to protect hepatocytes from the deleterious detergent activity of bile salts (PubMed:21820390). Does not confer multidrug resistance (By similarity).

Translocation activity is inhibited by the ATPase inhibitor vanadate and the calcium channel blocker verapamil (PubMed:17523162, PubMed:23468132). Translocation activity is enhanced by the addition of the bile salt taurocholate (PubMed:17523162, PubMed:23468132).

Cholestasis of pregnancy, intrahepatic 3 (ICP3) [MIM:614972]: A liver disorder of pregnancy. It presents during the second or, more commonly, the third trimester of pregnancy with intense pruritus which becomes more severe with advancing gestation and cholestasis. It causes fetal distress, spontaneous premature delivery and intrauterine death. Patients have spontaneous and progressive disappearance of cholestasis after delivery. Cholestasis results from abnormal biliary transport from the liver into the small intestine. {ECO:0000269 PubMed:10767346, ECO:0000269 PubMed:12746424, ECO:0000269 PubMed:15077010}. Note=The disease is caused by mutations affecting the gene represented in this entry.

Gallbladder disease 1 (GBD1) [MIM:600803]: One of the major digestive diseases. Gallstones composed of cholesterol (cholelithiasis) are the common manifestations in western countries. Most people with gallstones, however, remain asymptomatic through their lifetimes. {ECO:0000269 PubMed:11313316, ECO:0000269 PubMed:12891548, ECO:0000269 PubMed:22331132, ECO:0000269 PubMed:23533021, ECO:0000269 PubMed:24723470, ECO:0000269 PubMed:28012258, ECO:0000269 Ref.2}. Note=The disease is caused by mutations affecting the gene represented in this entry.

No data available for
Genatlas
for ABCB4 Gene

Publications for ABCB4 Gene

A new splicing site mutation of the ABCB4 gene in intrahepatic cholestasis of pregnancy with raised serum gamma-GT.(PMID: 19261551)Tavian D … Coviello DA(Digestive and liver disease : official journal of the Italian Society of Gastroenterology and the Italian Association for the Study of the Liver 2009)34224458